labatt, what year is your X5. The facelift one has adaptive brake light so it will flicker if you put on the LED taillight without the resistor. No problem on the pre-facelift. There's no point to put on a set of non-LED aftermarket taillights.
These are good.

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00 E39 DINAN S1 //M5 (82k miles)
06 E53 DINAN 4.8iS, born 2/18/2006 (126k miles) http://www.xoutpost.com/bmw-sav-foru...s-my-dslr.html
90 Straman Z32 TwinTurbo Convertible, (1 of 44 ever made) 5 speed, 444rwhp/451rwtq
01 360 Novitec Spider F1 (26k miles)